Suction servomotor with follow-up device



Patented July 15, 1947 SUCTION SERVOMOTOR WITH FoLLow-UP DEVICE p YAlfred B. Metsger, United States Navy Application July 1, 1943, SerialNo. 493,140

1 Claim. (01.121441) (Granted under the act of. Mai-ch 3, ma es amendedApril so, 1928; 310 0. (3.751)

The present invention relates: to a suction'servo force multiplier ordevice designed to produce a motion nearly equal to that of a straightline input of motion, but with much greater force, and deriving.operating power froma suction, and from a gas under pressure in whichthe whole device operates.

Expressing the above in more specific terms, a device isprovided whichis provided withra casing or body having an operating cylinder chamber,slidably operating on a fixedly mounted piston. An extension on the saidcasing encloses a valve chamber, with ducts connecting the two chambers,and an axially moving plunger slidably operating in the valve chamber,its motion being controlled by any separate means and constituting theinput to this device, and adapted to close the ends of the connectionducts to control the output of the force multiplier.

When the device is quiescent and the valve chamber plunger is in aposition equally restricting the ends of the connection ducts where theyenter the valve chamber, the pressure in both ends of the cylindercasing is substantially equal to that in the suction line. But when thevalve chamber plunger is moved to further uncover the valve chamber endof.one of the connection ducts, the pressure in the ends of the cylinderis made unequal on the opposed sides of a piston therein, by the inflowof gas of a, higher pressure, such as the atmosphere, through the valvechamber and said connection duct. In which event, the cylinder casingmoves along on the fixed piston, and motion of the whole body of thedevice takes place in a straight line motion which can be used to drivea connecting rod or other means of utilization of the power output inaccordance with the valve chamber plunger. The exact nature of theinvention will be more particularly described and its advantagesexplained as the specification proceeds herein.

In the accompanying drawings forming part of the present specification:

Fig. 1 is a horizontal central longitudinal section of the device takenon line I--I of Fig. 2.

Fig. 2 is an end view of the exterior of Fig. 1.

In the drawings the numeral I indicates a cylinder body or casing whichcontains the cylinder operating chamber 2, which is divided into twosubsidiary chambers 3 and 4 by the piston head 5, which last is carriedon the piston rod 6 and forms a piston.

The piston as seen from Fig. 1 of the drawings is fixed to a suitablebase 8 by means of piston rod and the upright 24, but the cylinder bodyI slidably operates on the piston head 5.

The cylinde body I, has an air or gas exit passage 9, with an exit portI0, through which air or gas may be exhausted by the suction .pipe

II. A pair of restricted area orifices I2 and I3' I are provided forpermitting gas or air-to flow from the respectivesub-chambers land 3 ofthe piston chamber V x The casing I has an extension- I4 in which islocated a valve chamber I5, anda pair of air ducts orpassages I6, I Lthrough which air may-be admitted from the valve chamber I5 totheoperating chambers 4 and 3 respectively. I q r -In the valve chamberI5 islocatedan input plunger I8 having ahead I9, and a'stem ZD, and

- it is seen the stem of said plunger is operated by some externalmotion appliance such as 26.

The annular grooves 2|, 22 in extension I4 slidably operate with respectto the plunger head I9. The valve chamber I5 has an orifice 23, and alsoanother 21 around plunger stem I8, at the top of the valve chamber,through which air or gas coming from the surrounding region passes toannular grooves 22 or 2| respectively, except that it will be noted theplunger head I9 when in a neutral position restricts the flow of airthrough the ducts I6 and I! to a negligible amount. When said flow isnegligible through ducts I6 and II, the pressures in the operatingchambers 3, 4 are equal to the pressure in the suction air line I I. Themotion of said body I, is used to drive a pivoted connecting rod 25 orother means of power output for the device.

When the plunger I8 and head I9 leave the equilibrium position as shown,one of the grooves 2| or 22 is opened, admitting gas to one of theoperating chambers 3 or 4. Since the admission port 23 or 21 is muchlarger than the corresponding restricted passage I2 or I3, the pressurein the connecting chamber approaches the pressure of the gas surroundingthe device and admitted through orifice 23 or 21 to the annular groove22, or 2i and duct I6 or IT.

The resulting pressures in chamber 3 or 4 move the body casting I tofollow the plunger I8, until the plunger and body casting I, are againin the equilibrium relation.

Since the motion of the body I in a straight line over piston 5 may beused to drive a connecting rod 25 or other means of output of mechanicalpower, it is seen a motion and power equal to that of a straight lineinput is obtained by the present device but with much greater forcederiving operating power from suction of air or gas, and the surroundinggas pressure, in which the device is located.

The invention described herein may be manufactured and used by or forthe Government of the United States of America for governmental purposeswithout the payment of any royalties thereon or therefor.

I claim:

A double acting piston and cylinder unit in which the main piston isstationarily fixed by means of a rigidly mounted piston rod passingthrough onmend-zof theecylinder, and the.-cylin assume: the neutralpositiemt stop the moveder is slidabliv mountedfir deliveringrafbrceax'e mentofiitheicylirrder. V

ially within the limits of the piston chamber, ALFRED B. METSGER. theopposite ends of said chamber being com-e nected by restricted portstowaicommon suction REFERENCES CITED line, a piston Valve having aCasing integrarmtfii E The following references are of record in the aidcylinder and comprising a piston and stem fil f this patent;

for movement parallel to said cylindenxaiboree for said valve pistonterminatingin shoulders. UNITED STATES PATENTS for limiting the movementof'said'valve piston 10 Number Name Date therein and having a pair ofaxially-spacedLan- 3 39 Dungan Man 4, 1373 nular grooves unrestrictedlyconnectediby pprts 1 5 Edwards sept 14, 20 to opposite ends of the mainpistonh chambery 15931350: e n Sept 7, 92 the outer edges of saidannular grooves being 1,361,529 Harding June '7 932 spaced at a slightlygreater distance than the 15 13337335 Sperry 3, 932 lngtl'r' o-fthewe-lve piston wherebywlien the 3923359 DgMbnge- 2.1;- 19 3 valve -isin n'eutral pesition; reducedbutiequa-l 1323344 'v k' Sept; 2 -933pressures will result on both sides ofthe-main 2 101357" Wo -3; 1933-piston and when=the va1ve is moved in either 2; 345531 Ganam 23 4directionfrom neutral positiem atmospheric 20 2353592- Cunningham" u y 5944 pressure on the-corresponding side of' themain piston-will cause thecylinder to" deliver a" sub- FOREIGN PATENTS stantial force inthe-samedirection; depending Number Country Dateonthe diameter of the pistonchamber; for the 6673 3 France 1929 same" distance, whereupon the-valvewill-again 25

